For guiding media, such as liquids, gases or electricity, elongated parts, such as hoses, tubes or cables are used, which often need to be guided through a wall opening, e.g. through the opening of a housing of an electrical device.
In the chemical industry, the pharmaceutical industry and the food industry strict requirements are prescribed with regard to the cleanness of production facilities and all their components. Thereby it is important that openings, through which elongated parts are guided, are tightly sealed. Further, feed-through devices shall not suffer from contamination or corrosion and shall not require extensive cleaning or maintenance.
In patent document EP1898506B1 (corresponding to DE102006043217B3), a feed-through device is known, that comprises a hollow cylindrical tubular fitting, which can be connected to a housing wall and that comprises an outer thread, on which a cap nut is mounted that is provided with an inner thread. With the cap nut a hollow cylindrical pressure element and an annular sealing element can be pressed against an elongated part that is guided through the tubular fitting.
According to EP1898506B1, the problem with such feed-through devices existed, that even after completely setting up a cap nut on the tubular fitting, a part of the outer thread of the tubular fitting remained exposed to the outside. Hence, this part of the outer threat could still get contaminated by dirt, wherefore the strict requirement of cleanness often could not be met.
In EP1898506B1, it is further explained that the outer thread of the tubular fitting of known feed-through devices cannot be manufactured with such a low number of convolutions of the outer thread that the cap nut in the installed state covers the outer thread completely in every configuration. Depending on the diameter of the elongated part guided through the feed-through device, the cap nut needs to be screw with more or less turns onto the tubular fitting, so that the pressure element and the sealing member can be pressed firmly and tightly against the elongated part. Hence, convolutions of the outer thread that are not covered are prone to contamination that can only be removed with considerable effort.
Hence, in EP1898506B1 it has been proposed to connect the cap nut of the feed-through device in such a way with the tubular fitting that the cap nut can be turned but cannot move axially against the tubular fitting and that the outer thread of the tubular fitting is completely covered. For this purpose the inner side of the cap nut comprises an inner thread that engages into an outer thread of a sliding element, which is arranged torque proof but slidable in the direction of the longitudinal axis of the tubular fitting. Hence, in this embodiment of the feed-through device, instead of the cap nut the sliding element is used as pressure element.
For connection purposes, the cap nut is brought from the outside onto the tubular fitting and is coupled by means of a snap on connection with the tubular fitting. Hence, the tubular fitting can be manufactured without an outer thread, wherefore the leading cause for contamination of the outside of the tubular fitting has fallen away.
For mounting the cap nut it is proposed, to insert a plastic ring into an annular groove provided on the outside of the tubular fitting, which plastic ring is pressed radially inwards when the cap nut is set up. Hence, in this embodiment additional device parts are required, which need to be manufactured and assembled with considerable effort. If the cap nut shall securely be held, then the plastic ring must be provided in massive form. However, in this case, considerable force is required to compress the plastic ring for setting-up the cap nut on the tubular fitting. However, if the plastic ring is designed with reduced dimensions, then the resulting connection may not be as reliable as required. Further, the plastic ring is under a load, which can lead to its destruction. Still further, the plastic ring has no sealing property, wherefore an additional sealing ring must be applied, which is exposed to mechanical stress when the cap nut is turned. Furthermore, the sliding element, which is slidably held within the cap nut, needs to be supported accordingly, so that it will not be blocked when handling the device.
In total a complex solution results with numerous device parts, that need to be manufactured, assembled and operated with corresponding effort and that are exposed to considerable stress.
In patent document EP1675244B1, a feed-through device is disclosed, that comprises a tubular fitting, a cap nut screwed onto the tubular fitting as well as a sealing and pressure member arranged between the tubular fitting and the cap nut, which sealing and pressure member consists of a single part, namely an elastic sealing insert. Also with this feed-through device a part of the outer thread of the tubular fitting can get freely exposed, particularly then, when an elongated part is installed that comprises a larger diameter. Furthermore, the threaded connection between the tubular fitting and the cap nut is not optimally sealed.
The present invention is based on the object of providing an improved feed-through device that allows sealed feed-through of elongated parts through opening of a wall, e.g. through a wall of a housing.
Particularly, a feed-through device shall be created, which can receive and sealingly embrace elongated parts with different diameters, thus providing a reliable sealing.
The feed-through device shall have a compact construction and shall exhibit smooth external surfaces, on which contamination can scarcely settle and which can be cleaned with little effort. Particularly, it shall be avoided that a part of a thread is exposed to the outside.
Furthermore, the feed-through device shall be created cost-efficient with a simple design and with the lowest possible number of device parts.
Still further, the feed-through device shall easily be operable and shall not be exposed to grow and stresses during operation, so that wearing is avoided. More particularly, only robust device elements shall be used that can be exposed to higher mechanical stresses, so that a robust construction results.